(A) Field of the Invention
The present invention is related to a Multiple-Input Multiple-Output (MIMO) detector and the detection method thereof, and more specifically, to a low complexity scalable MIMO detector and the detection method thereof.
(B) Description of the Related Art
Previous researches have shown that the channel capacity increases linearly with the number of transmitter and receiver antennas. MIMO communication systems can increase the channel capacity without additional bandwidth. Therefore, MIMO is promising to achieve high data rate requirements by spatial multiplexing technology.
There are many MIMO receiving technology for spatial multiplexing. These technologies can be divided into linear and non-linear detection methods. It is well known that the linear detection methods have lower complexity than non-linear ones. However, the linear detection methods have poor performance. Maximum-Likelihood (ML) detector and Vertical Bell Laboratories Layered Space Time (VBLAST) detector are two famous non-linear MIMO detection methods. Both technologies can provide performance gain over non-linear MIMO systems at the same data rate. However, the complexity of ML detection increases rapidly with the number of the antennas and the constellation size. In other words, the ML detection is not practical in large MIMO systems. The VBLAST detection was proposed by Foschini in 1996, and is also called Ordered Successive Interference Cancellation (OSIC) as its detection process.
Both of the ML detector and the VBLAST detector have their own advantages. The ML outperforms to VBLAST, while VBLAST has less computational complexity than ML. Previous researches tried to take advantages of these two detection methods, respectively. However, the results show the performance and complexity are in trade-off between ML and VBLAST, and the complexity is still high.